The United States Immunization Survey (USIS) has been conducted yearly by the Bureau of the Census in conjunction with the Center for Disease Control. Histories are obtained from randomly selected households throughout the country on immunization against diphtheria, pertussis, tetanus, poliomyelitis, rubella, measles, and mumps, and varicella on children 0-14 years of age. Results have been tabulated and published on immunization and disease rates by age, major geographic area, and crude designations of socio-economic status. During the national surveys, however, a wealth of data has been collected on household composition, employment, education, source of immunization, race, and other socio-economic and cultural characteristics which, although available, have not yet been analyzed in relation to patterns of vaccine utilization or disease occurrence. The basic objective of this proposal is to take advantage of this data base by obtaining the tapes, and to then perform a detailed epidemiologic study of the determinants of vaccine utilization and also a precise description of the factors affecting distribution of measles and chicken pox infections. The results should be of benefit in the formulation of local and national immunization policy.